According to “Klaus Lipinski (publisher): Lexikon der Datenkommunikation [Lexicon of Data Communications], 1995, 3rd edition, DATACOMM Buchverlag”, physical topology is defined as the configuration of network nodes and connections. The possible logical connections of network nodes are called logical topology. Logical topology indicates which node pairs can communicate with one another and whether they are directly physically connected to one another. The physical and logical topology need not be identical in networks. Known network topologies are star, tree, ring and bus.
The prior (§3 para. 2 No. 2 Patent Act and Art. 54 para. 3 EPC) European patent application No. 001123168.5 discloses a method for dynamic access to automation resources, whereby in a distributed automation system with a number of automation components a first automation component which looks for an automation resource sends a request to the automation system, and in response to this request receives from all reachable automation components a response concerning available suitable automation resources, and then selects the automation component with the suitable automation resource and uses the automation resource.
The invention consists of specifying a method with which at any time the current topology of an automation system can be determined, so that it is easier to locate individual stations, for instance for maintenance purposes.
This object is achieved according to the invention with the features of Claim 1. To this end a method is provided for determining the network topology of the distributed automation system with a plurality of automation devices connected thereto with the following steps:
First a first automation device, e.g. a programming device temporarily connected to the bus, sends a request to the automation system. Each automation device reached by the request then sends a response to the first automation device containing information on the position of the automation device that has been reached. Finally the first automation device generates a representation of the network topology of the distributed automation system from all the responses.
The advantage of the invention consists in the fact that manual determination of the network topology, for instance from what is known as configuration data, which is time-consuming and prone to error, is avoided and the network topology of the automation system can be determined automatically with the method according to the invention and above all on an up-to-date basis. The representation of the network topology determined can then be adapted to individual requirements, since all information is available electronically.
The dependent claims are directed at preferred embodiments of the present invention.
The method according to the invention is advantageously designed such that the first automation device sends the request to each automation device directly connected to it and each automation device reached by the request forwards the request to each further automation device directly connected to it in each case. In this way the number of communication procedures is reduced and it is not necessary to make a distinction between valid requests and other requests arriving later, to which there is no longer any need to reply and which are thus implicitly invalid.
If each automation device reached by the request which has a port for a peripheral device sends back information about the connected process peripheral devices, the determined network topology includes not only the topology of the communication users directly or indirectly connected to the bus, but also devices provided for controlling and/or monitoring an external technical process. Expanding a network topology in this way also makes it easier to locate such process peripheral devices in an extensive and complex system.
Advantageously the information on the position of the automation device reached includes a location code of the automation device reached. With this information it is possible to generate a topology of the automation system in respect of the geographical location of the individual communication users in the automation system.
Additionally advantageously the information on the position of the automation device reached includes a network address of the automation device reached.